DocumentPartner.ClosedXML a .NET library for reading, manipulating and writing Excel can use for .NET 8

 

Converting HTML to PDF with QuestPDF in .NET 8

QuestPDF is a powerful open-source library for generating PDFs in .NET. While it doesn't have a direct HTML-to-PDF conversion feature, you can leverage its capabilities to achieve similar results. Here's a breakdown of the approach:

1. Installation:

• Install the QuestPDF NuGet package in your .NET 8 project. You can use the Package Manager Console within your IDE or search for it in the NuGet Package Manager GUI.

2. Code Structure:

Here's a basic example demonstrating how to use QuestPDF to generate a PDF from HTML content:

C#

using QuestPDF;
using QuestPDF.Fluent;
using System.Text.Encodings.Utf8;

public class HtmlToPdfConverter
{
    public static Document GeneratePdfFromHtml(string htmlContent)
    {
        var document = Document.Create(container =>
        {
            container.Page(page =>
            {
                // Assuming your HTML content is already sanitized and safe
                var html = Encoding.UTF8.GetBytes(htmlContent);

                page.Content().Element(element =>
                {
                    // Custom logic to parse and render your HTML content
                    element.Raw(html, MimeType.TextHtml);
                });
            });
        });

        return document;
    }
}

Explanation:

• The GeneratePdfFromHtml method takes the HTML content as a string argument.
• A new Document object is created using the Document.Create method.
• Inside the document container, a Page element is defined.
• The Content property of the page is used to add a custom Element.
• This element uses the Raw method to directly embed the HTML content as bytes (encoded in UTF-8) with the MimeType.TextHtml specification.

3. Custom HTML Parsing (Optional):

The provided code snippet demonstrates a basic approach. In real-world scenarios, you might want to:

• Sanitize HTML: Ensure the HTML content is safe and free of potential security vulnerabilities before embedding it in the PDF. Libraries like SanitizeHtml can help with this.
• Advanced Parsing: If your HTML structure is complex, you might consider using libraries like HtmlAgilityPack to parse the HTML and then translate it into QuestPDF elements for more granular control over the layout and styling.

4. Generating the PDF:

Once you have your document object, you can use QuestPDF's functionalities to:

• Set document properties like title, author, etc.
• Add headers, footers, and other page elements.
• Include images or other content using QuestPDF's rich layout capabilities.

Finally, use the GeneratePdf method of the document object to generate the final PDF file and save it to a desired location.

5. Preview Considerations:

• QuestPDF itself doesn't provide a built-in preview functionality. However, you can leverage its rendering capabilities to create a simplified or low-resolution version of the final PDF for preview purposes. This can be displayed in a separate window or UI element within your application.

Further Resources:

• QuestPDF Documentation: https://github.com/QuestPDF
• SanitizeHtml Library: https://github.com/mganss/HtmlSanitizer
• HtmlAgilityPack Library: https://www.nuget.org/packages/HtmlAgilityPack/

By combining QuestPDF's layout capabilities with potential HTML parsing and preview techniques, you can achieve a solution for generating PDFs from HTML content in your .NET 8 application. Remember to adapt the code and approach based on your specific HTML complexity and desired preview functionality.